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Background: Salmonella enterica subsp. enterica serovar Montevideo (antigenic formula 6,7,14:g,m,[p],s:[1,2,7]) is a serovar of the O:7 (C₁) serogroup. This serovar was first isolated in Uruguay in 1936 from an infant with chronic enterocolitis. The Centers for Disease Control and Prevention (CDC) routinely includes serovar Montevideo among its top 20 Salmonella serotypes associated with human infections, causing an average of 700 illnesses in US each year. While serovar Montevideo ranked as the predominant Salmonella serotype in North America, it was not among the top five most reported serotypes in other continents.

NCBI PD link for serovar Montevideo: https://www.ncbi.nlm.nih.gov/pathogens/isolates/#(taxgroup_name:%22Salmonella%20enterica%22)%20AND%20computed_types:(%22serotype=Montevideo%22)

Genetic characteristics: Serovar Montevideo was found to be Chen et al. found that serovar Montevideo is polyphyletic with four clades identified. Within the largest clade, Montevideo A, the subclade Montevideo A-10 was cattle-associated, whereas Montevideo A-7 was associated with environmental sources (e.g., water, sediment). The cattle-associated Montevideo-A-10 lineage (emerged ~1905) contained two clonal subclades, Montevideo-A-10-I (29% of isolates, emerged ~1968) and Montevideo-A-10-II (13% of isolates, emerged ~1958), both showing increased cattle-associated prevalence over time. Lalsiamthara and Lee used serovar Montevideo and Typhimurium to infect chickens and rabbits. They revealed that infected birds showed no visible signs of illness, and histopathology revealed only mild damage to intestinal epithelium and splenic parenchyma despite consistent serovar Montevideo isolation from these tissues. Salmonella Montevideo was internalized by chicken peritoneal macrophages at rates comparable to Salmonella Typhimurium but demonstrated greater susceptibility to chicken serum complement than rabbit serum. In mock-infected layers, serovar Montevideo caused transient internal egg contamination at trace levels, persisting for one week post-inoculation, suggesting infection of Salmonella Montevideo in chickens is asymptomatic and sub-clinical. 

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